If
a sysctl is added to overwrite (file/directory) data on delete, I would
suggest at least 3 settings, 1) none, 2) background, low priority
overwrite, 3) atomic blocking, ie the rm command doesn't return until
successful overwrite completes.
I don't think it is going to be expensive to zero the directory entry on delete. We are not talking about the data (only the metadata).
Oh I thought the conversation had expanded to over writing old file data too, which would seem a grater value add than the dirent overwrite.